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   1 /*
   2  * linux/fs/9p/mux.c
   3  *
   4  * Protocol Multiplexer
   5  *
   6  *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
   7  *  Copyright (C) 2004-2005 by Latchesar Ionkov <lucho@ionkov.net>
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License as published by
  11  *  the Free Software Foundation; either version 2 of the License, or
  12  *  (at your option) any later version.
  13  *
  14  *  This program is distributed in the hope that it will be useful,
  15  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  *  GNU General Public License for more details.
  18  *
  19  *  You should have received a copy of the GNU General Public License
  20  *  along with this program; if not, write to:
  21  *  Free Software Foundation
  22  *  51 Franklin Street, Fifth Floor
  23  *  Boston, MA  02111-1301  USA
  24  *
  25  */
  26
  27 #include <linux/config.h>
  28 #include <linux/module.h>
  29 #include <linux/errno.h>
  30 #include <linux/fs.h>
  31 #include <linux/poll.h>
  32 #include <linux/kthread.h>
  33 #include <linux/idr.h>
  34 #include <linux/mutex.h>
  35
  36 #include "debug.h"
  37 #include "v9fs.h"
  38 #include "9p.h"
  39 #include "conv.h"
  40 #include "transport.h"
  41 #include "mux.h"
  42
  43 #define ERREQFLUSH      1
  44 #define SCHED_TIMEOUT   10
  45 #define MAXPOLLWADDR    2
  46
  47 enum {
  48         Rworksched = 1,         /* read work scheduled or running */
  49         Rpending = 2,           /* can read */
  50         Wworksched = 4,         /* write work scheduled or running */
  51         Wpending = 8,           /* can write */
  52 };
  53
  54 struct v9fs_mux_poll_task;
  55
  56 struct v9fs_req {
  57         int tag;
  58         struct v9fs_fcall *tcall;
  59         struct v9fs_fcall *rcall;
  60         int err;
  61         v9fs_mux_req_callback cb;
  62         void *cba;
  63         struct list_head req_list;
  64 };
  65
  66 struct v9fs_mux_data {
  67         spinlock_t lock;
  68         struct list_head mux_list;
  69         struct v9fs_mux_poll_task *poll_task;
  70         int msize;
  71         unsigned char *extended;
  72         struct v9fs_transport *trans;
  73         struct v9fs_idpool tagpool;
  74         int err;
  75         wait_queue_head_t equeue;
  76         struct list_head req_list;
  77         struct list_head unsent_req_list;
  78         struct v9fs_fcall *rcall;
  79         int rpos;
  80         char *rbuf;
  81         int wpos;
  82         int wsize;
  83         char *wbuf;
  84         wait_queue_t poll_wait[MAXPOLLWADDR];
  85         wait_queue_head_t *poll_waddr[MAXPOLLWADDR];
  86         poll_table pt;
  87         struct work_struct rq;
  88         struct work_struct wq;
  89         unsigned long wsched;
  90 };
  91
  92 struct v9fs_mux_poll_task {
  93         struct task_struct *task;
  94         struct list_head mux_list;
  95         int muxnum;
  96 };
  97
  98 struct v9fs_mux_rpc {
  99         struct v9fs_mux_data *m;
 100         struct v9fs_req *req;
 101         int err;
 102         struct v9fs_fcall *rcall;
 103         wait_queue_head_t wqueue;
 104 };
 105
 106 static int v9fs_poll_proc(void *);
 107 static void v9fs_read_work(void *);
 108 static void v9fs_write_work(void *);
 109 static void v9fs_pollwait(struct file *filp, wait_queue_head_t * wait_address,
 110                           poll_table * p);
 111 static u16 v9fs_mux_get_tag(struct v9fs_mux_data *);
 112 static void v9fs_mux_put_tag(struct v9fs_mux_data *, u16);
 113
 114 static DEFINE_MUTEX(v9fs_mux_task_lock);
 115 static struct workqueue_struct *v9fs_mux_wq;
 116
 117 static int v9fs_mux_num;
 118 static int v9fs_mux_poll_task_num;
 119 static struct v9fs_mux_poll_task v9fs_mux_poll_tasks[100];
 120
 121 int v9fs_mux_global_init(void)
 122 {
 123         int i;
 124
 125         for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++)
 126                 v9fs_mux_poll_tasks[i].task = NULL;
 127
 128         v9fs_mux_wq = create_workqueue("v9fs");
 129         if (!v9fs_mux_wq)
 130                 return -ENOMEM;
 131
 132         return 0;
 133 }
 134
 135 void v9fs_mux_global_exit(void)
 136 {
 137         destroy_workqueue(v9fs_mux_wq);
 138 }
 139
 140 /**
 141  * v9fs_mux_calc_poll_procs - calculates the number of polling procs
 142  * based on the number of mounted v9fs filesystems.
 143  *
 144  * The current implementation returns sqrt of the number of mounts.
 145  */
 146 static int v9fs_mux_calc_poll_procs(int muxnum)
 147 {
 148         int n;
 149
 150         if (v9fs_mux_poll_task_num)
 151                 n = muxnum / v9fs_mux_poll_task_num +
 152                     (muxnum % v9fs_mux_poll_task_num ? 1 : 0);
 153         else
 154                 n = 1;
 155
 156         if (n > ARRAY_SIZE(v9fs_mux_poll_tasks))
 157                 n = ARRAY_SIZE(v9fs_mux_poll_tasks);
 158
 159         return n;
 160 }
 161
 162 static int v9fs_mux_poll_start(struct v9fs_mux_data *m)
 163 {
 164         int i, n;
 165         struct v9fs_mux_poll_task *vpt, *vptlast;
 166         struct task_struct *pproc;
 167
 168         dprintk(DEBUG_MUX, "mux %p muxnum %d procnum %d\n", m, v9fs_mux_num,
 169                 v9fs_mux_poll_task_num);
 170         mutex_lock(&v9fs_mux_task_lock);
 171
 172         n = v9fs_mux_calc_poll_procs(v9fs_mux_num + 1);
 173         if (n > v9fs_mux_poll_task_num) {
 174                 for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++) {
 175                         if (v9fs_mux_poll_tasks[i].task == NULL) {
 176                                 vpt = &v9fs_mux_poll_tasks[i];
 177                                 dprintk(DEBUG_MUX, "create proc %p\n", vpt);
 178                                 pproc = kthread_create(v9fs_poll_proc, vpt,
 179                                                    "v9fs-poll");
 180
 181                                 if (!IS_ERR(pproc)) {
 182                                         vpt->task = pproc;
 183                                         INIT_LIST_HEAD(&vpt->mux_list);
 184                                         vpt->muxnum = 0;
 185                                         v9fs_mux_poll_task_num++;
 186                                         wake_up_process(vpt->task);
 187                                 }
 188                                 break;
 189                         }
 190                 }
 191
 192                 if (i >= ARRAY_SIZE(v9fs_mux_poll_tasks))
 193                         dprintk(DEBUG_ERROR, "warning: no free poll slots\n");
 194         }
 195
 196         n = (v9fs_mux_num + 1) / v9fs_mux_poll_task_num +
 197             ((v9fs_mux_num + 1) % v9fs_mux_poll_task_num ? 1 : 0);
 198
 199         vptlast = NULL;
 200         for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++) {
 201                 vpt = &v9fs_mux_poll_tasks[i];
 202                 if (vpt->task != NULL) {
 203                         vptlast = vpt;
 204                         if (vpt->muxnum < n) {
 205                                 dprintk(DEBUG_MUX, "put in proc %d\n", i);
 206                                 list_add(&m->mux_list, &vpt->mux_list);
 207                                 vpt->muxnum++;
 208                                 m->poll_task = vpt;
 209                                 memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
 210                                 init_poll_funcptr(&m->pt, v9fs_pollwait);
 211                                 break;
 212                         }
 213                 }
 214         }
 215
 216         if (i >= ARRAY_SIZE(v9fs_mux_poll_tasks)) {
 217                 if (vptlast == NULL)
 218                         return -ENOMEM;
 219
 220                 dprintk(DEBUG_MUX, "put in proc %d\n", i);
 221                 list_add(&m->mux_list, &vptlast->mux_list);
 222                 vptlast->muxnum++;
 223                 m->poll_task = vptlast;
 224                 memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
 225                 init_poll_funcptr(&m->pt, v9fs_pollwait);
 226         }
 227
 228         v9fs_mux_num++;
 229         mutex_unlock(&v9fs_mux_task_lock);
 230
 231         return 0;
 232 }
 233
 234 static void v9fs_mux_poll_stop(struct v9fs_mux_data *m)
 235 {
 236         int i;
 237         struct v9fs_mux_poll_task *vpt;
 238
 239         mutex_lock(&v9fs_mux_task_lock);
 240         vpt = m->poll_task;
 241         list_del(&m->mux_list);
 242         for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
 243                 if (m->poll_waddr[i] != NULL) {
 244                         remove_wait_queue(m->poll_waddr[i], &m->poll_wait[i]);
 245                         m->poll_waddr[i] = NULL;
 246                 }
 247         }
 248         vpt->muxnum--;
 249         if (!vpt->muxnum) {
 250                 dprintk(DEBUG_MUX, "destroy proc %p\n", vpt);
 251                 send_sig(SIGKILL, vpt->task, 1);
 252                 vpt->task = NULL;
 253                 v9fs_mux_poll_task_num--;
 254         }
 255         v9fs_mux_num--;
 256         mutex_unlock(&v9fs_mux_task_lock);
 257 }
 258
 259 /**
 260  * v9fs_mux_init - allocate and initialize the per-session mux data
 261  * Creates the polling task if this is the first session.
 262  *
 263  * @trans - transport structure
 264  * @msize - maximum message size
 265  * @extended - pointer to the extended flag
 266  */
 267 struct v9fs_mux_data *v9fs_mux_init(struct v9fs_transport *trans, int msize,
 268                                     unsigned char *extended)
 269 {
 270         int i, n;
 271         struct v9fs_mux_data *m, *mtmp;
 272
 273         dprintk(DEBUG_MUX, "transport %p msize %d\n", trans, msize);
 274         m = kmalloc(sizeof(struct v9fs_mux_data), GFP_KERNEL);
 275         if (!m)
 276                 return ERR_PTR(-ENOMEM);
 277
 278         spin_lock_init(&m->lock);
 279         INIT_LIST_HEAD(&m->mux_list);
 280         m->msize = msize;
 281         m->extended = extended;
 282         m->trans = trans;
 283         idr_init(&m->tagpool.pool);
 284         init_MUTEX(&m->tagpool.lock);
 285         m->err = 0;
 286         init_waitqueue_head(&m->equeue);
 287         INIT_LIST_HEAD(&m->req_list);
 288         INIT_LIST_HEAD(&m->unsent_req_list);
 289         m->rcall = NULL;
 290         m->rpos = 0;
 291         m->rbuf = NULL;
 292         m->wpos = m->wsize = 0;
 293         m->wbuf = NULL;
 294         INIT_WORK(&m->rq, v9fs_read_work, m);
 295         INIT_WORK(&m->wq, v9fs_write_work, m);
 296         m->wsched = 0;
 297         memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
 298         m->poll_task = NULL;
 299         n = v9fs_mux_poll_start(m);
 300         if (n)
 301                 return ERR_PTR(n);
 302
 303         n = trans->poll(trans, &m->pt);
 304         if (n & POLLIN) {
 305                 dprintk(DEBUG_MUX, "mux %p can read\n", m);
 306                 set_bit(Rpending, &m->wsched);
 307         }
 308
 309         if (n & POLLOUT) {
 310                 dprintk(DEBUG_MUX, "mux %p can write\n", m);
 311                 set_bit(Wpending, &m->wsched);
 312         }
 313
 314         for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
 315                 if (IS_ERR(m->poll_waddr[i])) {
 316                         v9fs_mux_poll_stop(m);
 317                         mtmp = (void *)m->poll_waddr;   /* the error code */
 318                         kfree(m);
 319                         m = mtmp;
 320                         break;
 321                 }
 322         }
 323
 324         return m;
 325 }
 326
 327 /**
 328  * v9fs_mux_destroy - cancels all pending requests and frees mux resources
 329  */
 330 void v9fs_mux_destroy(struct v9fs_mux_data *m)
 331 {
 332         dprintk(DEBUG_MUX, "mux %p prev %p next %p\n", m,
 333                 m->mux_list.prev, m->mux_list.next);
 334         v9fs_mux_cancel(m, -ECONNRESET);
 335
 336         if (!list_empty(&m->req_list)) {
 337                 /* wait until all processes waiting on this session exit */
 338                 dprintk(DEBUG_MUX, "mux %p waiting for empty request queue\n",
 339                         m);
 340                 wait_event_timeout(m->equeue, (list_empty(&m->req_list)), 5000);
 341                 dprintk(DEBUG_MUX, "mux %p request queue empty: %d\n", m,
 342                         list_empty(&m->req_list));
 343         }
 344
 345         v9fs_mux_poll_stop(m);
 346         m->trans = NULL;
 347
 348         kfree(m);
 349 }
 350
 351 /**
 352  * v9fs_pollwait - called by files poll operation to add v9fs-poll task
 353  *      to files wait queue
 354  */
 355 static void
 356 v9fs_pollwait(struct file *filp, wait_queue_head_t * wait_address,
 357               poll_table * p)
 358 {
 359         int i;
 360         struct v9fs_mux_data *m;
 361
 362         m = container_of(p, struct v9fs_mux_data, pt);
 363         for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++)
 364                 if (m->poll_waddr[i] == NULL)
 365                         break;
 366
 367         if (i >= ARRAY_SIZE(m->poll_waddr)) {
 368                 dprintk(DEBUG_ERROR, "not enough wait_address slots\n");
 369                 return;
 370         }
 371
 372         m->poll_waddr[i] = wait_address;
 373
 374         if (!wait_address) {
 375                 dprintk(DEBUG_ERROR, "no wait_address\n");
 376                 m->poll_waddr[i] = ERR_PTR(-EIO);
 377                 return;
 378         }
 379
 380         init_waitqueue_entry(&m->poll_wait[i], m->poll_task->task);
 381         add_wait_queue(wait_address, &m->poll_wait[i]);
 382 }
 383
 384 /**
 385  * v9fs_poll_mux - polls a mux and schedules read or write works if necessary
 386  */
 387 static void v9fs_poll_mux(struct v9fs_mux_data *m)
 388 {
 389         int n;
 390
 391         if (m->err < 0)
 392                 return;
 393
 394         n = m->trans->poll(m->trans, NULL);
 395         if (n < 0 || n & (POLLERR | POLLHUP | POLLNVAL)) {
 396                 dprintk(DEBUG_MUX, "error mux %p err %d\n", m, n);
 397                 if (n >= 0)
 398                         n = -ECONNRESET;
 399                 v9fs_mux_cancel(m, n);
 400         }
 401
 402         if (n & POLLIN) {
 403                 set_bit(Rpending, &m->wsched);
 404                 dprintk(DEBUG_MUX, "mux %p can read\n", m);
 405                 if (!test_and_set_bit(Rworksched, &m->wsched)) {
 406                         dprintk(DEBUG_MUX, "schedule read work mux %p\n", m);
 407                         queue_work(v9fs_mux_wq, &m->rq);
 408                 }
 409         }
 410
 411         if (n & POLLOUT) {
 412                 set_bit(Wpending, &m->wsched);
 413                 dprintk(DEBUG_MUX, "mux %p can write\n", m);
 414                 if ((m->wsize || !list_empty(&m->unsent_req_list))
 415                     && !test_and_set_bit(Wworksched, &m->wsched)) {
 416                         dprintk(DEBUG_MUX, "schedule write work mux %p\n", m);
 417                         queue_work(v9fs_mux_wq, &m->wq);
 418                 }
 419         }
 420 }
 421
 422 /**
 423  * v9fs_poll_proc - polls all v9fs transports for new events and queues
 424  *      the appropriate work to the work queue
 425  */
 426 static int v9fs_poll_proc(void *a)
 427 {
 428         struct v9fs_mux_data *m, *mtmp;
 429         struct v9fs_mux_poll_task *vpt;
 430
 431         vpt = a;
 432         dprintk(DEBUG_MUX, "start %p %p\n", current, vpt);
 433         allow_signal(SIGKILL);
 434         while (!kthread_should_stop()) {
 435                 set_current_state(TASK_INTERRUPTIBLE);
 436                 if (signal_pending(current))
 437                         break;
 438
 439                 list_for_each_entry_safe(m, mtmp, &vpt->mux_list, mux_list) {
 440                         v9fs_poll_mux(m);
 441                 }
 442
 443                 dprintk(DEBUG_MUX, "sleeping...\n");
 444                 schedule_timeout(SCHED_TIMEOUT * HZ);
 445         }
 446
 447         __set_current_state(TASK_RUNNING);
 448         dprintk(DEBUG_MUX, "finish\n");
 449         return 0;
 450 }
 451
 452 /**
 453  * v9fs_write_work - called when a transport can send some data
 454  */
 455 static void v9fs_write_work(void *a)
 456 {
 457         int n, err;
 458         struct v9fs_mux_data *m;
 459         struct v9fs_req *req;
 460
 461         m = a;
 462
 463         if (m->err < 0) {
 464                 clear_bit(Wworksched, &m->wsched);
 465                 return;
 466         }
 467
 468         if (!m->wsize) {
 469                 if (list_empty(&m->unsent_req_list)) {
 470                         clear_bit(Wworksched, &m->wsched);
 471                         return;
 472                 }
 473
 474                 spin_lock(&m->lock);
 475 again:
 476                 req = list_entry(m->unsent_req_list.next, struct v9fs_req,
 477                                req_list);
 478                 list_move_tail(&req->req_list, &m->req_list);
 479                 if (req->err == ERREQFLUSH)
 480                         goto again;
 481
 482                 m->wbuf = req->tcall->sdata;
 483                 m->wsize = req->tcall->size;
 484                 m->wpos = 0;
 485                 dump_data(m->wbuf, m->wsize);
 486                 spin_unlock(&m->lock);
 487         }
 488
 489         dprintk(DEBUG_MUX, "mux %p pos %d size %d\n", m, m->wpos, m->wsize);
 490         clear_bit(Wpending, &m->wsched);
 491         err = m->trans->write(m->trans, m->wbuf + m->wpos, m->wsize - m->wpos);
 492         dprintk(DEBUG_MUX, "mux %p sent %d bytes\n", m, err);
 493         if (err == -EAGAIN) {
 494                 clear_bit(Wworksched, &m->wsched);
 495                 return;
 496         }
 497
 498         if (err <= 0)
 499                 goto error;
 500
 501         m->wpos += err;
 502         if (m->wpos == m->wsize)
 503                 m->wpos = m->wsize = 0;
 504
 505         if (m->wsize == 0 && !list_empty(&m->unsent_req_list)) {
 506                 if (test_and_clear_bit(Wpending, &m->wsched))
 507                         n = POLLOUT;
 508                 else
 509                         n = m->trans->poll(m->trans, NULL);
 510
 511                 if (n & POLLOUT) {
 512                         dprintk(DEBUG_MUX, "schedule write work mux %p\n", m);
 513                         queue_work(v9fs_mux_wq, &m->wq);
 514                 } else
 515                         clear_bit(Wworksched, &m->wsched);
 516         } else
 517                 clear_bit(Wworksched, &m->wsched);
 518
 519         return;
 520
 521       error:
 522         v9fs_mux_cancel(m, err);
 523         clear_bit(Wworksched, &m->wsched);
 524 }
 525
 526 static void process_request(struct v9fs_mux_data *m, struct v9fs_req *req)
 527 {
 528         int ecode, tag;
 529         struct v9fs_str *ename;
 530
 531         tag = req->tag;
 532         if (!req->err && req->rcall->id == RERROR) {
 533                 ecode = req->rcall->params.rerror.errno;
 534                 ename = &req->rcall->params.rerror.error;
 535
 536                 dprintk(DEBUG_MUX, "Rerror %.*s\n", ename->len, ename->str);
 537
 538                 if (*m->extended)
 539                         req->err = -ecode;
 540
 541                 if (!req->err) {
 542                         req->err = v9fs_errstr2errno(ename->str, ename->len);
 543
 544                         if (!req->err) {        /* string match failed */
 545                                 PRINT_FCALL_ERROR("unknown error", req->rcall);
 546                         }
 547
 548                         if (!req->err)
 549                                 req->err = -ESERVERFAULT;
 550                 }
 551         } else if (req->tcall && req->rcall->id != req->tcall->id + 1) {
 552                 dprintk(DEBUG_ERROR, "fcall mismatch: expected %d, got %d\n",
 553                         req->tcall->id + 1, req->rcall->id);
 554                 if (!req->err)
 555                         req->err = -EIO;
 556         }
 557
 558         if (req->err == ERREQFLUSH)
 559                 return;
 560
 561         if (req->cb) {
 562                 dprintk(DEBUG_MUX, "calling callback tcall %p rcall %p\n",
 563                         req->tcall, req->rcall);
 564
 565                 (*req->cb) (req->cba, req->tcall, req->rcall, req->err);
 566                 req->cb = NULL;
 567         } else
 568                 kfree(req->rcall);
 569
 570         v9fs_mux_put_tag(m, tag);
 571
 572         wake_up(&m->equeue);
 573         kfree(req);
 574 }
 575
 576 /**
 577  * v9fs_read_work - called when there is some data to be read from a transport
 578  */
 579 static void v9fs_read_work(void *a)
 580 {
 581         int n, err;
 582         struct v9fs_mux_data *m;
 583         struct v9fs_req *req, *rptr, *rreq;
 584         struct v9fs_fcall *rcall;
 585         char *rbuf;
 586
 587         m = a;
 588
 589         if (m->err < 0)
 590                 return;
 591
 592         rcall = NULL;
 593         dprintk(DEBUG_MUX, "start mux %p pos %d\n", m, m->rpos);
 594
 595         if (!m->rcall) {
 596                 m->rcall =
 597                     kmalloc(sizeof(struct v9fs_fcall) + m->msize, GFP_KERNEL);
 598                 if (!m->rcall) {
 599                         err = -ENOMEM;
 600                         goto error;
 601                 }
 602
 603                 m->rbuf = (char *)m->rcall + sizeof(struct v9fs_fcall);
 604                 m->rpos = 0;
 605         }
 606
 607         clear_bit(Rpending, &m->wsched);
 608         err = m->trans->read(m->trans, m->rbuf + m->rpos, m->msize - m->rpos);
 609         dprintk(DEBUG_MUX, "mux %p got %d bytes\n", m, err);
 610         if (err == -EAGAIN) {
 611                 clear_bit(Rworksched, &m->wsched);
 612                 return;
 613         }
 614
 615         if (err <= 0)
 616                 goto error;
 617
 618         m->rpos += err;
 619         while (m->rpos > 4) {
 620                 n = le32_to_cpu(*(__le32 *) m->rbuf);
 621                 if (n >= m->msize) {
 622                         dprintk(DEBUG_ERROR,
 623                                 "requested packet size too big: %d\n", n);
 624                         err = -EIO;
 625                         goto error;
 626                 }
 627
 628                 if (m->rpos < n)
 629                         break;
 630
 631                 dump_data(m->rbuf, n);
 632                 err =
 633                     v9fs_deserialize_fcall(m->rbuf, n, m->rcall, *m->extended);
 634                 if (err < 0) {
 635                         goto error;
 636                 }
 637
 638                 rcall = m->rcall;
 639                 rbuf = m->rbuf;
 640                 if (m->rpos > n) {
 641                         m->rcall = kmalloc(sizeof(struct v9fs_fcall) + m->msize,
 642                                            GFP_KERNEL);
 643                         if (!m->rcall) {
 644                                 err = -ENOMEM;
 645                                 goto error;
 646                         }
 647
 648                         m->rbuf = (char *)m->rcall + sizeof(struct v9fs_fcall);
 649                         memmove(m->rbuf, rbuf + n, m->rpos - n);
 650                         m->rpos -= n;
 651                 } else {
 652                         m->rcall = NULL;
 653                         m->rbuf = NULL;
 654                         m->rpos = 0;
 655                 }
 656
 657                 dprintk(DEBUG_MUX, "mux %p fcall id %d tag %d\n", m, rcall->id,
 658                         rcall->tag);
 659
 660                 req = NULL;
 661                 spin_lock(&m->lock);
 662                 list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
 663                         if (rreq->tag == rcall->tag) {
 664                                 req = rreq;
 665                                 req->rcall = rcall;
 666                                 list_del(&req->req_list);
 667                                 spin_unlock(&m->lock);
 668                                 process_request(m, req);
 669                                 break;
 670                         }
 671
 672                 }
 673
 674                 if (!req) {
 675                         spin_unlock(&m->lock);
 676                         if (err >= 0 && rcall->id != RFLUSH)
 677                                 dprintk(DEBUG_ERROR,
 678                                         "unexpected response mux %p id %d tag %d\n",
 679                                         m, rcall->id, rcall->tag);
 680                         kfree(rcall);
 681                 }
 682         }
 683
 684         if (!list_empty(&m->req_list)) {
 685                 if (test_and_clear_bit(Rpending, &m->wsched))
 686                         n = POLLIN;
 687                 else
 688                         n = m->trans->poll(m->trans, NULL);
 689
 690                 if (n & POLLIN) {
 691                         dprintk(DEBUG_MUX, "schedule read work mux %p\n", m);
 692                         queue_work(v9fs_mux_wq, &m->rq);
 693                 } else
 694                         clear_bit(Rworksched, &m->wsched);
 695         } else
 696                 clear_bit(Rworksched, &m->wsched);
 697
 698         return;
 699
 700       error:
 701         v9fs_mux_cancel(m, err);
 702         clear_bit(Rworksched, &m->wsched);
 703 }
 704
 705 /**
 706  * v9fs_send_request - send 9P request
 707  * The function can sleep until the request is scheduled for sending.
 708  * The function can be interrupted. Return from the function is not
 709  * a guarantee that the request is sent succesfully. Can return errors
 710  * that can be retrieved by PTR_ERR macros.
 711  *
 712  * @m: mux data
 713  * @tc: request to be sent
 714  * @cb: callback function to call when response is received
 715  * @cba: parameter to pass to the callback function
 716  */
 717 static struct v9fs_req *v9fs_send_request(struct v9fs_mux_data *m,
 718                                           struct v9fs_fcall *tc,
 719                                           v9fs_mux_req_callback cb, void *cba)
 720 {
 721         int n;
 722         struct v9fs_req *req;
 723
 724         dprintk(DEBUG_MUX, "mux %p task %p tcall %p id %d\n", m, current,
 725                 tc, tc->id);
 726         if (m->err < 0)
 727                 return ERR_PTR(m->err);
 728
 729         req = kmalloc(sizeof(struct v9fs_req), GFP_KERNEL);
 730         if (!req)
 731                 return ERR_PTR(-ENOMEM);
 732
 733         if (tc->id == TVERSION)
 734                 n = V9FS_NOTAG;
 735         else
 736                 n = v9fs_mux_get_tag(m);
 737
 738         if (n < 0)
 739                 return ERR_PTR(-ENOMEM);
 740
 741         v9fs_set_tag(tc, n);
 742
 743         req->tag = n;
 744         req->tcall = tc;
 745         req->rcall = NULL;
 746         req->err = 0;
 747         req->cb = cb;
 748         req->cba = cba;
 749
 750         spin_lock(&m->lock);
 751         list_add_tail(&req->req_list, &m->unsent_req_list);
 752         spin_unlock(&m->lock);
 753
 754         if (test_and_clear_bit(Wpending, &m->wsched))
 755                 n = POLLOUT;
 756         else
 757                 n = m->trans->poll(m->trans, NULL);
 758
 759         if (n & POLLOUT && !test_and_set_bit(Wworksched, &m->wsched))
 760                 queue_work(v9fs_mux_wq, &m->wq);
 761
 762         return req;
 763 }
 764
 765 static void v9fs_mux_flush_cb(void *a, struct v9fs_fcall *tc,
 766                               struct v9fs_fcall *rc, int err)
 767 {
 768         v9fs_mux_req_callback cb;
 769         int tag;
 770         struct v9fs_mux_data *m;
 771         struct v9fs_req *req, *rptr;
 772
 773         m = a;
 774         dprintk(DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m, tc,
 775                 rc, err, tc->params.tflush.oldtag);
 776
 777         spin_lock(&m->lock);
 778         cb = NULL;
 779         tag = tc->params.tflush.oldtag;
 780         list_for_each_entry_safe(req, rptr, &m->req_list, req_list) {
 781                 if (req->tag == tag) {
 782                         list_del(&req->req_list);
 783                         if (req->cb) {
 784                                 cb = req->cb;
 785                                 req->cb = NULL;
 786                                 spin_unlock(&m->lock);
 787                                 (*cb) (req->cba, req->tcall, req->rcall,
 788                                        req->err);
 789                         }
 790                         kfree(req);
 791                         wake_up(&m->equeue);
 792                         break;
 793                 }
 794         }
 795
 796         if (!cb)
 797                 spin_unlock(&m->lock);
 798
 799         v9fs_mux_put_tag(m, tag);
 800         kfree(tc);
 801         kfree(rc);
 802 }
 803
 804 static void
 805 v9fs_mux_flush_request(struct v9fs_mux_data *m, struct v9fs_req *req)
 806 {
 807         struct v9fs_fcall *fc;
 808
 809         dprintk(DEBUG_MUX, "mux %p req %p tag %d\n", m, req, req->tag);
 810
 811         fc = v9fs_create_tflush(req->tag);
 812         v9fs_send_request(m, fc, v9fs_mux_flush_cb, m);
 813 }
 814
 815 static void
 816 v9fs_mux_rpc_cb(void *a, struct v9fs_fcall *tc, struct v9fs_fcall *rc, int err)
 817 {
 818         struct v9fs_mux_rpc *r;
 819
 820         if (err == ERREQFLUSH) {
 821                 kfree(rc);
 822                 dprintk(DEBUG_MUX, "err req flush\n");
 823                 return;
 824         }
 825
 826         r = a;
 827         dprintk(DEBUG_MUX, "mux %p req %p tc %p rc %p err %d\n", r->m, r->req,
 828                 tc, rc, err);
 829         r->rcall = rc;
 830         r->err = err;
 831         wake_up(&r->wqueue);
 832 }
 833
 834 /**
 835  * v9fs_mux_rpc - sends 9P request and waits until a response is available.
 836  *      The function can be interrupted.
 837  * @m: mux data
 838  * @tc: request to be sent
 839  * @rc: pointer where a pointer to the response is stored
 840  */
 841 int
 842 v9fs_mux_rpc(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
 843              struct v9fs_fcall **rc)
 844 {
 845         int err;
 846         unsigned long flags;
 847         struct v9fs_req *req;
 848         struct v9fs_mux_rpc r;
 849
 850         r.err = 0;
 851         r.rcall = NULL;
 852         r.m = m;
 853         init_waitqueue_head(&r.wqueue);
 854
 855         if (rc)
 856                 *rc = NULL;
 857
 858         req = v9fs_send_request(m, tc, v9fs_mux_rpc_cb, &r);
 859         if (IS_ERR(req)) {
 860                 err = PTR_ERR(req);
 861                 dprintk(DEBUG_MUX, "error %d\n", err);
 862                 return PTR_ERR(req);
 863         }
 864
 865         r.req = req;
 866         dprintk(DEBUG_MUX, "mux %p tc %p tag %d rpc %p req %p\n", m, tc,
 867                 req->tag, &r, req);
 868         err = wait_event_interruptible(r.wqueue, r.rcall != NULL || r.err < 0);
 869         if (r.err < 0)
 870                 err = r.err;
 871
 872         if (err == -ERESTARTSYS && m->trans->status == Connected && m->err == 0) {
 873                 spin_lock(&m->lock);
 874                 req->tcall = NULL;
 875                 req->err = ERREQFLUSH;
 876                 spin_unlock(&m->lock);
 877
 878                 clear_thread_flag(TIF_SIGPENDING);
 879                 v9fs_mux_flush_request(m, req);
 880                 spin_lock_irqsave(&current->sighand->siglock, flags);
 881                 recalc_sigpending();
 882                 spin_unlock_irqrestore(&current->sighand->siglock, flags);
 883         }
 884
 885         if (!err) {
 886                 if (r.rcall)
 887                         dprintk(DEBUG_MUX, "got response id %d tag %d\n",
 888                                 r.rcall->id, r.rcall->tag);
 889
 890                 if (rc)
 891                         *rc = r.rcall;
 892                 else
 893                         kfree(r.rcall);
 894         } else {
 895                 kfree(r.rcall);
 896                 dprintk(DEBUG_MUX, "got error %d\n", err);
 897                 if (err > 0)
 898                         err = -EIO;
 899         }
 900
 901         return err;
 902 }
 903
 904 #if 0
 905 /**
 906  * v9fs_mux_rpcnb - sends 9P request without waiting for response.
 907  * @m: mux data
 908  * @tc: request to be sent
 909  * @cb: callback function to be called when response arrives
 910  * @cba: value to pass to the callback function
 911  */
 912 int v9fs_mux_rpcnb(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
 913                    v9fs_mux_req_callback cb, void *a)
 914 {
 915         int err;
 916         struct v9fs_req *req;
 917
 918         req = v9fs_send_request(m, tc, cb, a);
 919         if (IS_ERR(req)) {
 920                 err = PTR_ERR(req);
 921                 dprintk(DEBUG_MUX, "error %d\n", err);
 922                 return PTR_ERR(req);
 923         }
 924
 925         dprintk(DEBUG_MUX, "mux %p tc %p tag %d\n", m, tc, req->tag);
 926         return 0;
 927 }
 928 #endif  /*  0  */
 929
 930 /**
 931  * v9fs_mux_cancel - cancel all pending requests with error
 932  * @m: mux data
 933  * @err: error code
 934  */
 935 void v9fs_mux_cancel(struct v9fs_mux_data *m, int err)
 936 {
 937         struct v9fs_req *req, *rtmp;
 938         LIST_HEAD(cancel_list);
 939
 940         dprintk(DEBUG_MUX, "mux %p err %d\n", m, err);
 941         m->err = err;
 942         spin_lock(&m->lock);
 943         list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
 944                 list_move(&req->req_list, &cancel_list);
 945         }
 946         spin_unlock(&m->lock);
 947
 948         list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
 949                 list_del(&req->req_list);
 950                 if (!req->err)
 951                         req->err = err;
 952
 953                 if (req->cb)
 954                         (*req->cb) (req->cba, req->tcall, req->rcall, req->err);
 955                 else
 956                         kfree(req->rcall);
 957
 958                 kfree(req);
 959         }
 960
 961         wake_up(&m->equeue);
 962 }
 963
 964 static u16 v9fs_mux_get_tag(struct v9fs_mux_data *m)
 965 {
 966         int tag;
 967
 968         tag = v9fs_get_idpool(&m->tagpool);
 969         if (tag < 0)
 970                 return V9FS_NOTAG;
 971         else
 972                 return (u16) tag;
 973 }
 974
 975 static void v9fs_mux_put_tag(struct v9fs_mux_data *m, u16 tag)
 976 {
 977         if (tag != V9FS_NOTAG && v9fs_check_idpool(tag, &m->tagpool))
 978                 v9fs_put_idpool(tag, &m->tagpool);
 979 }